Alternative asset manager became a billionaire alongside Michael Novogratz and Peter Briger Jr. last February with public offering of Fortress Investment Group. Former Lehman Brothers partner founded Fortress in 1998 with Robert Kauffman and Randal Nardone. Novogratz and Briger joined 4 years later. Shares down 60% since offering. Group sold minority interest to Japanese investment firm Nomura for $890 million in 2006; each has also earned more than $100 million in net cash payouts since 2005. Edens studied finance at Oregon State, led private equity division at Black Rock Financial. Then Lehman. Now Fortress chief executive; manages private equity, publicly traded alternative investment businesses.